Today, video systems incorporate digital network cameras that are capable of communicating image data using TCP/IP protocols. These video systems are displacing traditional surveillance systems that are based on analog closed-circuit television (CCTV) cameras. For example, and in contrast to analog CCTV cameras, video systems with digital network cameras capture and encode raw image data in real time to generate high-resolution compressed video content for continuous or discrete transmission to any number of recipients or storage devices.
Compressed, high-resolution video content may be transmitted to designated recipients for live viewing or storage devices for archiving, either continuously or alternatively. A network camera may transmit image data in response to, for example, one or more discrete triggering events or incidents. To achieve efficient bit-rate coding of the compressed video content, network cameras may include video codecs that employ differential encoding schemes. These encoding schemes may require large distances between intra-refresh frames. The compressed video content generated with such encoding schemes may have long group-of-picture (GOP) lengths that consume minimal network resources during transmission across a network.
Furthermore, and in contrast to the analog CCTV cameras, network cameras may also buffer a portion of the compressed video content, thereby enabling these network cameras to distribute compressed video content that brackets an event or incident of interest. However, due to the large distance between the intra-refresh frames, the use of long-GOP length codes in compressed video data increases the amount of memory necessary to store a complete sequence of encoded data. As a result, the limited buffer capacities of network cameras limit the ability of these cameras to buffer meaningful portions of the compressed video content.
In view of the foregoing, there is a need for improved systems and methods for encoding image data and generating compressed video content. Moreover, there is a need for improved systems and methods that generate virtual intra-frames to enable the buffering and delivery of compressed video content over a network. There is also a need for such systems and methods that support efficient, large GOP-length encoding of video data and the buffering of encoded frame data with a network camera having limited buffer memory. There is also a need for such systems and methods that can be implemented in a computer-based environment.